Generator quieting

so there you have it.

Ropdoc wrote:
youtube has interesting ideas. Just need to be carfeul of heat buildup. Genny needs to be cool.

Lots of terrible ideas as well, posted by those who clearly have no idea what they're doing :E ... FAR better examples are those shown in the link I provided earlier of Japanese designs which are based on sound engineering principles rather than uneducated guesswork. :R

youtube has interesting ideas. Just need to be carfeul of heat buildup. Genny needs to be cool.

profdant139 wrote:
That's the problem right there -- the cost/benefit ratio. That is probably why there are no commercially-available after-market generator boxes for the RV folks -- no one would pay more than about $200 (US or Canadian!) for that product.

..and why Honda doesn't have any worries about open frame gens in quiet boxes.

That's the problem right there -- the cost/benefit ratio. That is probably why there are no commercially-available after-market generator boxes for the RV folks -- no one would pay more than about $200 (US or Canadian!) for that product.

profdant139 wrote:
For the exhaust baffle, I think there is heat-proof insulation for home water heater chimneys -- it should not be too expensive. I should measure the temp of the exhaust area to see if there is a real fire danger.

Custom polycarbonate exhaust shrouds sold by Generator Line are rated to a moderate 250F so the 2000F batting I used is far beyond what is really required. Since I always use my quiet box in my Avalanche's rear cargo compartment I was thinking of dispensing with the plastic box entirely by simply enclosing the generator with a "box" formed with this West Marine Noise Control Barrier. Since it's a relatively stiff material I'd mount the same intake fan I'm currently using directly on the intake end wall, forget using an exhaust baffle, and instead exhaust directly out using a Generator Line exhaust shroud. If the foam needed any additional strengthening the outside of the foam enclosure could be reinforced with a lightweight plastic product such as Coroplast which is often used to enclose a trailer underbelly and which can be purchased at stores such as Home Depot. This design would certainly be lighter than any plastic or wood box lined with the same noise barrier and could probably just be set in place over the generator. The only reason I haven't proceeded with this idea is the significant cost of the noise barrier material and the Generator Line exhaust shroud which together could easily be $500 Cdn at the current exchange rate. :E

For the exhaust baffle, I think there is heat-proof insulation for home water heater chimneys -- it should not be too expensive. I should measure the temp of the exhaust area to see if there is a real fire danger.

profdant139 wrote:
As far as I can tell, the most cost-effective sound deadening material is called Homasote -- it is sold under a variety of names. Essentially, it comes in half inch thick sheets, 4 feet by 8 feet, and it is compressed cellulose.

Maybe there is a cost-effective way to waterproof the cellulose sheeting? And to use something else for the exhaust baffle.

I first tried a sheet product that sounds much like Homasote but it didn't work at all as it was way too heavy and crumbled easily. Any quiet box I've looked at online that's demonstrated excellent results has always used dense noise control barrier foam such as that product I link to earlier from West Marine. I have to admit I'm SO tempted to try it myself, except my wife would kill me if she knew I spent that much to buy a sheet of it. :E. As I mentioned earlier jauguston gifted me a piece of high temperature batting that I used for the exhaust box but had that not been available to me I think I'd have used Roxul stone wool, the only problem being I'd have had to pay for a whole bag of it when all I needed was a small piece.

As far as I can tell, the most cost-effective sound deadening material is called Homasote -- it is sold under a variety of names. Essentially, it comes in half inch thick sheets, 4 feet by 8 feet, and it is compressed cellulose. It sells for about ten or eleven dollars a sheet. You could line the interior of a plastic box with this stuff, and it would not be too heavy, I think. (Obviously, there would have to be an air intake and an exhaust port, with baffles.)

The main problem with Homasote is that it is not weather-proof at all -- a little water and it turns to mush. The other concern is whether it is sufficiently heat resistant for the exhaust baffle -- I would guess it is not.

Maybe there is a cost-effective way to waterproof the cellulose sheeting? And to use something else for the exhaust baffle.

There are commercially available soundproofing materials available for exterior applications, but they are very expensive.

profdant139 wrote:
I was deterred by the complexity of his design. I think yours is much more feasible and affordable.

FWIW you'll notice jauguston used a multi chamber exhaust baffle to incrementally reduce exhaust noise ... I did as well in my first interpretation but because I was using an already existing plastic box instead of one custom made for the purpose I ended up mounting the baffle external to the box because there wasn't sufficient room inside the box. It seemed to work well enough but it sure was ungainly hanging off the one end of the box and added a lot of additional weight so I cut it down to the single chamber you see in my pics so it can direct exhaust straight up and vent out of my Avalanche's storage compartment. Although his multi chamber design would logically seem to be more effective I can't say I noticed much difference myself between the two approaches.